The Great Outdoors - A Performance Enhancing Drug for Men

If you handed men a pill that lowered their blood pressure, sharpened their mood, strengthened their immune system, reduced their stress, improved their energy and sleep, while supporting healthy testosterone, and which also helped them live longer — with no side effects and no cost — they would take it every single day.

That "pill" already exists. It's called going outside.

Especially for men over 40, the outdoors isn't a soft science wellness add-on. It's one of the most evidence-based, no-cost interventions available for the various health concerns that actually shorten men's lives: heart disease, chronic stress, declining hormones, and the slow erosion of fitness and mental health. Below is what the research shows — included with a simple outdoors prescription you can start with this week.

The "Minimum Effective Dose" Is Smaller Than You Think

In medicine we are always looking for the minimum effective dose of a drug, that is, the least amount of a medication needed to do the job. When it comes to the amount of “outside time” we men need for the minimum effective dose, the number is remarkably low. The most useful number in this entire field comes from a landmark study of nearly 20,000 adults in England. Researchers found that people who spent at least 120 minutes a week in natural environments were significantly more likely to report good health and high psychological well-being than those who spent none — with 59% higher odds of reporting good health and 23% higher odds of high well-being (White et al., Scientific Reports, 2019).

Three details make this finding genuinely practical and important for busy men:

· It didn't matter how you got there. One long Sunday hike or several short weekday walks with the dog produced the same benefits (University of Exeter / ScienceDaily).

· Below 120 minutes, however, the benefits largely disappeared — and above ~200–300 minutes, the return on investment flattened out. So, two to five hours a week seems to be the sweet spot for “outside time”. (White et al., Scientific Reports, 2019).

· It held across the board — older men, men with long-term illnesses, and men regardless of economic status all seemed to benefit equally (Reuters Health).

A word of honesty though: this was an observational study, so it shows a strong association rather than ironclad proof of cause and effect. But it does line up with a large body of experimental work below, and 120 minutes a week certainly seems to be a realistic, low-risk target and also relatively easy to attain for all men.

Your Heart Loves the Outdoors

Cardiovascular disease remains the leading killer of men globally, which makes any reduction in death or disability extremely important. A major systematic review of 143 studies found that a greater exposure to green space was associated with lower diastolic blood pressure, lower heart rate, reduced salivary cortisol (a marker for stress), and a reduced incidence of type 2 diabetes, as well as a lower all-cause and cardiovascular mortality (Twohig-Bennett & Jones, Environmental Research, 2018).

The effect wasn’t just about being outdoors — it's also about exercising outdoors. The concept of "green exercise" (physical activity in a natural setting) consistently outperforms the same workouts done indoors:

· In a controlled study, 20 minutes of light outdoor exercise lowered both systolic and diastolic blood pressure more than exercise alone. It also helped to improve both self-esteem and mood (Pretty et al., green exercise research).

· In patients with coronary artery disease, walking in a park produced greater improvements in cardiac function — blood pressure, heart rate, and cardiac output — than walking along busy city streets (American Council on Exercise).

· Time in nature is also associated with lower rates of hypertension (high blood pressure). One analysis estimated that up to 9% of high blood pressure cases could be prevented if everyone visited green space at least once a week for 30+ minutes. Frequent visitors to the outside were also significantly less likely to require blood-pressure medications (American Journal of Lifestyle Medicine, 2023).

Outdoor exercise also tends to make exercise feel easier. When people choose their own pace outdoors, they often walk faster while reporting a lower sense of effort — which translates into better long-term adherence (Extreme Physiology & Medicine, 2013). So, while keeping your gym membership all year round may be important to many Canadian men, there is a case for putting your membership on hold for the summer months and continuing your exercise routine in the great outdoors. Or, alternatively, change up your exercise program seasonally.

Sunlight, Vitamin D, and Testosterone

This is the information men ask about most — and it deserves a balanced answer.

There is a real, repeatedly observed link between vitamin D status and testosterone. A study of 2,299 men found that those with sufficient vitamin D had significantly higher testosterone, with levels peaking in late summer when sun exposure is highest (Manual, summarizing Wehr et al.). In a 12-month randomized controlled trial, men who took vitamin D supplements daily showed a statistically significant rise in total, free, and bioactive testosterone versus placebo (Pilz et al., Hormone and Metabolic Research).

Sunlight is the body's primary natural source of vitamin D: UVB rays on bare skin trigger its synthesis, and roughly 15–30 minutes of midday sun on the face, arms, and legs a few times a week can meaningfully support vitamin D levels (Rethink Testosterone summary). This, as those of us who live in Canada can attest, is difficult to do throughout much of the year. This is why Vitamin D supplementation is so important and some sun exposure when possible is crucial. There may also be a case to be made for a trip to a Caribbean Island sometime during the winter, but I digress. 

But here's the honest physician's caveat:

· The testosterone benefit appears to flow mainly through correcting a vitamin D deficiency. If your levels are already adequate, extra sun likely adds little hormonally (Rethink Testosterone). However, in my practice with Transform Men’s Health, I rarely find men with adequate Vitamin D levels even when tested at the end of the summer and especially if not supplemented in some meaningful way. 

· The relationship is correlational, and at least one controlled study found that a single bout of UV exposure did not acutely raise testosterone in older men (International Journal of Exercise Science, 2020). It takes time and effort to correct Vitamin D levels and therefore testosterone levels. You have to be consistent in your supplementation. Having said that, I often suggest men reduced their Vitamin D Supplementation over the summer months but not discontinue it altogether.

· Never burn. Skin cancer risk far outweighs any marginal hormonal gain with sun exposure. Get short, regular sun exposure, then cover up and/or apply sunscreen.

Bottom line: getting outside in daylight is a smart, natural way to support healthy vitamin D and, indirectly, testosterone — especially for men in northern climates during winter, who should also discuss supplementation with their doctor. This is why at Transform Men’s Health we consider Vitamin D one of the most important supplements for men. With living in our northern latitudes in Canada most men are deficient, when tested, for Vitamin D levels. Wearing a parka in the winter and a sunscreen in the summer, we often significantly restrict how much Vitamin D our bodies produce throughout the year. For this reason, it is often beneficial to continue Vitamin D supplementation even in the summer months. 

The Stress and Mental-Health Reset

Chronic stress is a quiet driver of many health concerns in men. They include high blood pressure, poor sleep, low testosterone, weight gain, metabolic dysfunction, heart disease, diminished mood and suppressed immunity — and men are often the least likely to address it directly. Nature offers a remarkably efficient and effective fix.

· Just 20–30 minutes sitting or walking in a natural setting produced the steepest drop in the stress hormone cortisol in a University of Michigan study — researchers literally called it the "nature pill" (Frontiers in Psychology / Harvard Health).

· In a brain-imaging study, a one-hour walk in nature decreased activity in the amygdala — the brain's threat-and-stress center — while an equivalent walk in the city did not (Sudimac et al., Molecular Psychiatry, 2022).

· A study highlighted by Men's Health Magazine found men who walked in nature felt more relaxed and less tired, had lower cortisol, and showed heart rate variability up to 30% higher — a marker of better recovery and cardiovascular resilience — than after urban or indoor walks (Men's Health, 2025).

The Immune Boost Hidden in the Forest

One of the most striking areas of research is "forest bathing" (shinrin-yoku), the Japanese practice of simply spending unhurried time among trees.

In a series of studies led by Dr. Qing Li at Nippon Medical School, a forest trip increased the activity of natural killer (NK) cells —the immune cells that hunt virus-infected and tumor cells — by roughly 50%, with the boost lasting more than 30 days after exposure (Li et al., Environmental Health and Preventive Medicine, 2009). The leading explanation: trees release airborne compounds called phytoncides that, once inhaled, enhance NK activity and anti-cancer protein expression (NutritionFacts.org summary).

A recent review concluded that forest bathing is associated with enhanced NK-cell activity, lower cortisol, reduced blood pressure and heart rate, and a shift toward calmer, parasympathetic nervous-system dominance — making it a "promising, low-risk strategy" for immune resilience and stress regulation (Medical Sciences review, 2026). Because the NK boost can persist for up to a month, even a monthly walk in the woods may help maintain it.

Your Outdoor Prescription

You don't need a wilderness expedition or expensive gear. Based on the evidence above, here's a simple, physician-style prescription any man can fill:

· Target 120+ minutes of nature per week. Aim for two to three hours; spread it out however fits your life. This is the threshold where benefits reliably appear.

· Move while you're out there. Walk, hike, cycle, or play tennis outdoors. "Green exercise" beats the gym for blood pressure, mood, and adherence — and feels easier. 

· Catch morning or midday daylight, skin exposed, without burning. 15–30 minutes a few times a week supports vitamin D and, through it, healthy testosterone. Cover up before you get a sunburn.

· Take a real "nature pill" when stressed. A 20–30-minute walk in a park or among trees measurably lowers cortisol and calms the brain's stress center.

· Visit the forest monthly. The immune (NK-cell) benefit of time among trees can last up to a month — so even occasional woodland trips pay off.

· Take a camping, canoeing, kayaking, hiking trip yearly. The benefits can be staggering. Even if only a few days or a few weeks. The benefits are measurable. The other benefit that should be shouted out loud is the ability to digitally detox. Meaning it is a time to leave the smart phone, emails, texts and social media behind for awhile and reconnect with your friends, family and nature without a digital leash. 

Personally, I have tried to do this yearly with my son since he was a little boy. Now a man with his own family, we have tried to continued this yearly event. This allows us a fixed time to paddle a canoe and camp in the woods together while perpetuating our unique experience and special time together. There is nothing more enjoyable, to me, than our life conversations while paddling a new lake or while sitting around a campfire at night. 

The Bottom Line: For men focused on living longer, stronger and better lives, the great outdoors checks every box: cardiovascular protection, hormonal support, stress reduction, immune strength, and a mood lift that you will feel immediately. The best part? The prescription is free, the side effects are good ones, and you can start filling the prescription the moment you step out of your front door.

This article is for general education and is not a substitute for individual medical advice. If you have heart disease, high blood pressure, low testosterone, or other health concerns, talk with your physician before making significant changes to your activity or sun exposure.